C.E. Evans wrote:
It's very easy if we go with the idea that the Voyager was just traveling carefully through the Delta Quadrant. Even so, there probably were instances in which the Voyager was moving at "plot speed" like other ships, even if only briefly to get from one star system to another.
I think there may have been an episode or two in Voyager that stated this, but weren't they mostly cruising at Warp 6 or 7 most of the show because the ship couldn't go past Warp 8 all the time? So this could account for some of the 70 year trip.
Ideally, it would be a case that most ships could safely
cruise at Warp 6 indefinitely, but cruise at higher warp speeds for correspondingly shorter and shorter periods of time due to the strain on both engines and spaceframe. Non-canon sources would have a ship's maximum warp reserved for relatively short emergency flights of up to twelve hours or so. But as with most things in Trek, there was never a set rule in regard to warp travel times and distances, although VOY did try more than other shows to keep some consistency to where the ship was in relation to home (in light-years) during its journeys.